1. Technical Field
The present invention relates to an ink composition for ink jet textile printing and an ink jet textile printing process.
2. Related Art
Disperse dyes are used for dyeing hydrophobic synthetic fibers such as polyester, nylon, and acetate. The disperse dyes do not have hydrophilic groups such as sulfonate groups and carboxyl groups and are therefore water-insoluble or low water-soluble. Accordingly, the disperse dyes are used in fine particle forms by being dispersed in aqueous media.
Technologies for dispersing fine particles of disperse dyes in aqueous media have been well known. Examples of a typical dipersant for dispersing a disperse dye in an aqueous medium include formalin condensates of naphthalenesulfonic acid and ligninsulfonic acids, and also include surfactants described in JP-A-48-14888, JP-A-50-100386, JP-A-54-2484, JP-A-55-54353, and JP-A-61-213273.
However, the use of fine particles of dye in a dispersed state has problems in that high temperature is necessary for sufficiently diffusing the fine particles of dye in synthetic fibers, such as polyester or nylon, as an object to be dyed and in that irregular color of the dyed matter is caused by sedimentation of the fine particles of dye. In addition, in an ink for ink jet textile printing, it is necessary to adjust the type and the amount of the dispersant to obtain a low viscosity. Therefore, sufficient stability cannot be realized to cause a decrease in storage stability in some cases. In order to solve these problems, it has been tried to solubilize a disperse dye in a solvent such as methylnaphthalene or n-butyl benzoate, instead of dispersing fine particles of disperse dye in an aqueous medium (for example, see Soeda, et al., “Development of ink by solubilization of disperse dye”, Bulletin of Tokyo Metropolitan Industrial Technology Research Institute, 2006, No. 1, pp. 74-75).
However, even if a disperse dye is solubilized in methylnaphthalene or n-butyl benzoate, it is necessary to further add a predetermined surfactant to the solvent in order to maintain the stable solubilization of the disperse dye in the solvent. As described above, in an ink jet textile printing ink containing a disperse dye, there has not been a solvent having, in a well-balanced manner, both lipophilicity for stably solubilizing disperse dyes and hydrophilicity necessary for a dyeing process by steaming.